The piezoelectric component is a monolithic multilayer ceramic piezoactuator. In a few embodiments such multilayer actuators feature porous, ceramic or metallic security layers (security structures). The porous security layers function as predetermined breaking points: Mechanical overloading of the stack of the piezoactuator especially results in the formation of cracks (polarization cracks) in these security layers. This means that a location definition and guidance of the polarization cracks occurring during a polarization or during operation is possible. The security layers can be formed from ceramic layers or from electrode layers (internal electrodes) of increased porosity.
For electrical contacting the internal electrodes are routed alternately to lateral sections of the stack surface isolated electrically from each other. Platings (external platings) are attached to these surface sections. The inner electrodes are connected alternately in parallel via these platings, which can be considered as a component of outer electrodes.
The stack of the piezoactuator is provided with a plastic sheath made from silicon. This plastic sheath is used for passivation of the stack. This means: The inner electrodes extending up to the lateral surfaces of the stack are electrically insulated and protected from mechanical destruction by the plastic sheathing.
When the silicon is attached to the surface of the stack there can be infiltration of silicon particles into the porous security layer. As a result of such an infiltration there can be decomposition of the silicon and decomposition products can be deposited especially in the area of the outer plating and directly below it by electrical discharges or mechanical compressive stresses. This can let a mechanical notch effect occur in the crack, which in its turn can lead to damage to the security layer and its environment. This can cause longitudinal cracks along the stacking direction of the stack. The component is thus predisposed to early failure.